Thursday, July 23, 2015

For some odd reason, maybe it was the slow season, Retraction Watch has caught up with the Journal of Economic Prospectives latest gremlin whacker (gremlins being the newest moles), aka correction of Richard Tol's 2009 article on the costs of climate change. Eli, of course, being the quick and dirty bunny he is had already had a say, but there remain things both interesting, perplexing and concerning about the paper, and indeed all of the papers that Richard cites for his paper, best seen in the figure displayed in the gremlin whacker linked above

The problem is that neither the discussion in the original paper, the WGII or pretty much anywhere else, does not reference baselines for each calculation or for the conglomeration of calculations.

This of course is irrelevant to the question of whether IAM calculations are worth a bucket of warm spit (this being a family blog, which a few exceptions when Dad Rabett goes nuclear).

The serious question is what is the baseline for each study and which sets the zero of the temperature scale? Did Poor Richard align the baseline for all the calculations. For which is the baseline pre-industrial (in which case the world is now past Tol’s outlying positive point at 1.0 C), 1860 or so when instrumental records start in which case the world is pretty close to it, or some more recent time, in which case, another couple of degrees would, at least according to Tol, have little effect.

Eli notes that Chris Field Hope's model, which underlies the Stern report, appears to be making a differential calculation, which, also raises some interesting Couéen questions by itself. Or, on the other hand, is there some agreed zero that you need to have the secret handshake to know about.

The caption to Figure 1 in the original The Economic Effects of Climate Change does offer this explanation:

"Note: Figure 1 shows 14 estimates of the global economic impact of climate change, expressed as the welfare-equivalent income gain or loss, as a function of the increase in global mean temperature relative to today. ...

While the data, title, and chart type have changed - the 'relative to today' part probably hasn't.

Eli, I have no idea what Tol is claiming - and frankly none of it makes much sense to me. If someone seriously believes a 5.5C rise in temperatures would result in a mere 6% reduction on globabl GDP they must also believe in Santa Clause.

More important, in these types of scenarios economics is devoid of morality - which fits Tol to a T considering his recent tweets. The man lacks integrity and I put him maybe a half-step above Moncton and Morano. All of them have some climbing to do to even reach the gutter.

Kevin O'Neill gives an answer, but unfortunately, he's been misled. You see, an update to the figure has a caption which says:

estimates of the global economic impact of climate change, expressed as the welfare-equivalent income gain or loss, as a function of the increase in the annual global mean surface air temperature relative to preindustrial times.

But it turns out that caption is wrong too. As it turns out, Tol didn't actually use any real baseline. All the papers used different temperature baselines, and Tol didn't put them on a common one! And as for his claims in his papers which said they were on particular baselines... well, um... those were... uh... not true.

If you'd like some details, there was some discussion of this topic at my site over a few topics. I think it was mostly on this and <a href="http://www.hi-izuru.org/wp_blog/2014/08/missing-the-obvious/</a> post. Put simply though, the work is complete and utter dreck.

It's not just the temperature baselines that are different. The rate of warming would affect how bad it is. That's different too. How much countries develop would affect how well they could adapt. That's different. How much populations would grow, and where, would affect how many people were in at-risk areas. That's different.

All of this raises the question of how did the AR5 came to rely so heavily on Tol's work in the first place? Perhaps it's as he himself said of the process; that Tol's papers were such a prominent part of the Impacts WG because "it favors initial scientific papers published on an issue, rather than the follow-up papers[.]"

Of course he meant to imply that it went after the most sensationalist, alarmist papers that would later have to be walked back by subsequent work tempering the results. Well, that's another thing he's been quite wrong about (as anybody keeping track of the IPCC reports over time would have been able to tell him).

I don't think I would use anything more flexible than a linear model for this dataset, and even then I would look at the predictive error bars and leverage etc. as it looks like there is at least one outlier.

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Eli Rabett

Eli Rabett, a not quite failed professorial techno-bunny who finally handed in the keys and retired from his wanna be research university. The students continue to be naive but great people and the administrators continue to vary day-to-day between homicidal and delusional without Eli's help. Eli notices from recent political developments that this behavior is not limited to administrators. His colleagues retain their curious inability to see the holes that they dig for themselves. Prof. Rabett is thankful that they, or at least some of them occasionally heeded his pointing out the implications of the various enthusiasms that rattle around the department and school. Ms. Rabett is thankful that Prof. Rabett occasionally heeds her pointing out that he is nuts.